Railways Transformed by On-site DX Signal and Communication: Safe Asset Management Supported by High-Precision Positioning

At the heart of safe railway operation are the signaling and communication installations placed alongside the tracks. Signals, level crossing mechanisms, track circuits, communication cables, and other infrastructure control train operations and enable information exchange between drivers and traffic control. Ensuring these installations are installed and maintained at precisely the correct locations is essential for on-time operation and accident prevention. Even slight installation errors or wiring mistakes can directly lead to accidents or operational troubles, so construction and management of these systems demand very high accuracy. However, traditional challenges such as ensuring positional accuracy and the constraints of the work environment have long affected the installation and maintenance work for signal and communication equipment in the field.

For example, installing even a single signal post requires meticulous surveying to place it exactly where the drawings specify. Even a tiny deviation in distance or angle from the track can affect signal sightlines or interfere with rolling stock. Despite this, fieldwork is often carried out at night, meaning accurate installations must be completed in limited time under darkness, placing a heavy burden on workers. Work areas beside the track are also very confined, and tasks must be performed while paying attention to high-speed trains passing by, so utmost care for safety is required.

Moreover, discrepancies between on-site conditions and design drawings pose another problem. Accumulated site modifications and emergency repairs over many years mean that the positions on drawings and the actual on-site positions often do not match. As a result, workers sometimes spend time searching for equipment based on drawings or comparing record photos with the site. Inaccurate past records for buried cables, for example, can create a risk of damaging other buried utilities during excavation. In addition, the aging and decline of field personnel is becoming more serious, making it increasingly difficult to maintain traditional methods. As a key to solving these field issues and achieving safe and efficient asset management, attention is focusing on the use of high-precision positioning RTK technology and AR (augmented reality) navigation. By combining smartphone-based RTK positioning to achieve centimeter-level accuracy, the so-called LRTK technology can dramatically transform installation and inspection work that used to rely on craftsmen’s intuition and manual labor. This article explains the problems with traditional methods and details the benefits that high-precision positioning with LRTK and AR construction navigation bring to railway signal and communication infrastructure management.

Field challenges encountered with traditional methods

• Laborious manual surveying and accuracy limits: For positioning signal posts or determining cable burial routes, analog surveying using tape measures or total stations was essential. But these analog methods require significant setup and measurement time, and ensuring accuracy has always been a major challenge in railway construction, which demands millimeter-level precision. Small measurement errors can lead to equipment misalignment, requiring fine adjustments or rework in later stages.

• Difficulty working at night and in confined sites: Working in the short nighttime windows after train operations is a major constraint. Trackside areas have narrow footing and limited lighting, forcing surveying and construction in poor visibility. Simply transporting and setting up heavy tripods and surveying instruments is burdensome, and sometimes there is nowhere to place the equipment. In such environments, positioning tasks take longer than usual and increase the physical load on workers.

• Inefficiency from multi-person manual operations: Traditional surveying and equipment installation presumed teamwork. For surveying, for example, two-person teams were needed—one holding the staff and the other operating the instrument—and checking signal visibility often required several people on site to erect mock signals. These labor- and procedure-intensive tasks are inefficient in terms of staffing and coordination, and in a context of worsening labor shortages they become a major burden. Securing personnel for such tasks is a critical issue in railway maintenance sites where chronic staff shortages persist.

• Risk of human error and rework: Human errors such as misreading survey values or marking mistakes are unavoidable. Careless transcription of coordinates from paper drawings, misreading dimensions, or misplacing marks can all cause equipment misplacement. If discrepancies are discovered after construction, major rework—such as re-pouring concrete foundations or replacing equipment—becomes necessary, severely impacting schedules and costs.

• Discrepancies between drawings and field conditions: Asset management also suffers when old drawings or ledger information do not match actual on-site layouts. Examples include route changes that were never reflected in drawings or coordinates recorded under older geodetic reference systems that no longer align with current systems. As a result, workers may waste time locating equipment on site or risk excavating the wrong spot. Reliance on drawings for inspections and construction brings inefficiencies due to these information gaps.

• Safety risks during work: The above circumstances create safety issues. Night work reduces alertness, and if surveyors enter areas close to the track, high places, or slopes to take measurements, the risk of accidents increases. Multiple people moving around in confined spaces also raises the chance of contact accidents. Conventional methods forced sites into a tense situation where pursuing efficiency and accuracy often compromised safety. In other words, field teams faced a dilemma in which it was difficult to balance work efficiency with safety.

High-precision positioning and AR construction navigation provided by LRTK

Emerging as a trump card to solve these traditional problems is the smartphone-based high-precision positioning system “LRTK.” LRTK (pronounced “L-R-T-K”) is a next-generation positioning system consisting of a small RTK-GNSS receiver that attaches to a smartphone and a dedicated app. RTK (Real Time Kinematic) technology corrects satellite positioning errors in real time to measure current location with centimeter-level accuracy (half-inch accuracy). GPS, which previously had errors on the order of meters, can with LRTK consistently provide location information almost perfectly aligned with design drawings. Attach an LRTK device to a smartphone and start it in an open sky area, and within about 30 seconds high-precision positioning stabilizes, turning the smartphone into a pocket-sized surveying instrument.

Particularly noteworthy is the AR construction navigation provided by LRTK. The target installation position is visually displayed on the smartphone camera feed, so workers are intuitively guided to the exact spot. For example, if the app is preloaded with the planned coordinates for a signal post, simply pointing the smartphone at the site will show real-time guidance such as “North ○ cm, East ○ cm to target.” By following the arrows and distance indicators, a worker can walk straight to the target; the point at which the distance reaches zero is the installation point. Ultimately a virtual stake or marker appears on the smartphone screen, indicating “this is the design-specified location” on the spot. The worker then only needs to drive a physical stake or make a mark there to complete accurate positioning. There is no longer any need to hold paper drawings and manually measure out dimensions. Thanks to AR-based position guidance, targets are not lost even at night or in complex terrain, and inexperienced staff can accurately place equipment at the intended point.

LRTK also includes functions for 3D point cloud (scanning) measurement. Using built-in smartphone LiDAR sensors and the like, surrounding structures and terrain can be scanned and recorded as point cloud data comprising tens of millions of points. Because RTK provides absolute coordinates (latitude, longitude, and elevation) for each point, the point cloud data obtained on site can be saved and used as a precise 3D model. For example, scanning the area around a newly installed signal allows later desktop verification of the signal’s height, tilt, and spatial relationship to nearby features. If cables are scanned before backfilling, the positions of underground cables can be preserved as digital data for future use. Point cloud data can be shared and viewed on the cloud, and on-site staff can easily take cross-sections to measure dimensions or automatically calculate backfill volumes. The captured point cloud data can also be used directly to update construction drawings or CIM models and connects smoothly to electronic submission of as-built documentation.

Position data, point clouds, and photos captured with LRTK are uploaded to the cloud in real time. This not only enables immediate data sharing between the field and the office, but also lets captured coordinates be plotted on maps for team-wide later reference. Photos taken with the smartphone are tagged with high-precision location information, eliminating uncertainty about where a photo was taken. Through this digital integration, asset locations that previously required cross-checking with drawings can now be intuitively managed on GIS maps and 3D models.

LRTK devices are very compact and cost-effective, making it easy to equip each worker to perform positioning and recording as needed. With LRTK deployment, on-site workflows change dramatically. One smartphone per person for positioning reduces the personnel previously required for surveying, and each worker can immediately measure locations and carry out installation tasks in their assigned area. With high-precision guidance, measurement mistakes are avoided and installations are completed correctly the first time, drastically reducing rework. This leads to shorter nighttime work durations and fewer people on site, markedly improving safety. Because work can be performed accurately using data rather than relying on veteran intuition, quality variation is reduced. LRTK offers a DX solution for railway infrastructure installation and maintenance that brings together efficiency, quality, and safety. In one reported case, using LRTK for stake-out at a construction site cut the time required for setting measurement points to about one-sixth compared with conventional optical surveying. The number of points that can be processed in a day increased dramatically, directly shortening project schedules and reducing costs.

Concrete on-site scenarios using LRTK

• Use for signal post installation: Traditionally, installing a new signal post required repeatedly measuring the distance from the track center to determine the foundation location and then checking sightlines from the driver’s perspective after installation. With LRTK, the smartphone navigates to the installation location based on design coordinates, allowing the base to be placed correctly at once. For example, even during late-night work, simply driving a stake at the location indicated by the AR marker on the smartphone completes the positioning process. Moreover, scanning the post after erection records its location so you can accurately check in the data whether the post is plumb and at the specified height. This streamlines visibility and clearance checks for signals and reduces the need for repeated on-site verification by large crews. Since large-scale manual confirmations are no longer necessary, the number of people working on the track at night is minimized, contributing to enhanced safety.

• Use for burying communication cables: When burying communication cables along railway lines, the conventional approach was to mark routes on the ground from drawings, then record the buried positions with photos and manual measurements after excavation. Inadequate records can leave risks of interference with other facilities during future excavations. With LRTK, AR visualization of the excavation route is possible before construction: pointing a smartphone at the ground displays the planned route as a line so workers can intuitively see where to dig. After burial, staff can scan the trench to record the exact position and depth of the cable as point cloud data in the cloud before backfilling. Later, simply viewing the ground through the smartphone enables AR visualization of underground cable locations, preventing accidental damage during other works. Because burial positions are preserved as accurate digital records, they can be easily shared with future construction teams, smoothing handovers and pre-construction coordination. Digitally retaining and utilizing buried-asset information greatly improves the quality of future maintenance.

• Use for inspection records of communication equipment: Field equipment related to signal communications requires regular inspection and adjustment. Historically, inspectors would carry drawings listing equipment numbers, complete checklists on site, and take photos. With LRTK, inspections are digitized. As a worker patrols with a smartphone, their current location is known with high accuracy, so which nearby assets require inspection is obvious on maps or via AR. Inspection results can be entered on the smartphone and photos saved to the cloud with location tags. For example, when inspecting the interior wiring of a level crossing control box, photos become automatically linked to the location, such as “internal wiring of control box on the north side of X level crossing,” which prevents confusion when preparing reports later. Past inspection histories can be viewed on maps, reducing oversights and missed inspections. If you want to check whether the installed equipment itself has moved or tilted, you can use scanned point cloud data to measure changes in tilt or position. With LRTK-driven data accumulation, maintenance work is visualized and recorded in real time, enabling field staff and management to share the same information for evaluating asset health. Completing data input and sharing on site also drastically reduces the post-work reporting burden and streamlines the entire maintenance cycle. Analyzing accumulated data also opens possibilities for developing predictive maintenance to detect early signs of failure.

Conclusion

The railway industry is at last entering a full-fledged era of on-site DX (digital transformation). The use of LRTK in signal and communication infrastructure management symbolizes this shift. Solutions that combine high-precision positioning, AR navigation, and 3D scanning transform work that used to rely on human hands into data-driven processes, dramatically improving safety, workmanship, and efficiency. The ability to complete accurate construction and inspections without errors even within limited nighttime work windows is invaluable for the teams that support safe train operation.

LRTK also has the major advantage of low barriers to on-site adoption. It does not require specialized machines or large-scale systems; simply attaching a small device to a smartphone lets staff start using it in their daily workflow. Because data are centrally managed in the cloud, the manual updating of paper drawings and ledgers is eliminated and tacit knowledge can be converted into shared organizational assets. From experienced veterans to newcomers, everyone can collaborate using the same digital tools, helping to close the generational gap. Real-time field data can be shared seamlessly with management and other departments, enabling the entire organization to grasp field conditions and make quick decisions.

The requirements for signal and communication asset management—“safe, certain, and rapid”—are precisely the outcomes that LRTK-driven on-site DX delivers. Smartphone RTK use is already spreading in domestic construction and civil engineering, and railway maintenance is following suit. The Ministry of Land, Infrastructure, Transport and Tourism is strongly promoting DX in the infrastructure sector, such as i-Construction, and with the full enforcement of the 2024 construction workstyle reform-related laws, reducing nighttime work hours has become an urgent task. In this context, introducing digital technologies like LRTK is a powerful solution that can simultaneously improve field productivity and ensure safety. To support increasingly complex and advanced infrastructure in the future, innovation in fieldwork itself is indispensable. The big transformation that starts with a small device will help secure the future of railway field operations. I truly hope you will adopt LRTK’s high-precision technology in the world of railway signal and communication transformed by on-site DX to achieve both safety and productivity. Now is the time when the field capability to protect railway safety can be further strengthened by digital power. Let us embrace digital technology and together pass on safe and resilient railway infrastructure to the next generation!